Asos has described as "inaccurate and misleading" claims its warehouse workers are paying a price for higher annual profits.

The online fashion retailer faced union criticism over working conditions at its Barnsley warehouse as it announced a 37% increase in underlying annual profits to £63.7m on the back of a 26% increase in sales to £1.4bn.

The GMB union's row with the company is similar to the one still simmering at Sports Direct, whichcovers allegations of poor treatment of warehouse staff.

Commenting on the company's results, the union's regional secretary Neil Derrick said: "We're seeing a familiar story play out - massive profits for those at the top, made on the back of poor pay, terms and conditions for those making 'fast fashion' a reality.

"Asos are quite literally coining it in while agency workers worry whether they'll get enough hours next week to pay the bills.

"We're simply asking Asos to treat the people who keep their warehouses moving with a bit of respect - that can't be too much to ask in the 21st century."

Asos chief executive Nick Beighton said on Tuesday: ''There has been comment recently in the media and elsewhere on working conditions in our warehouse which are inaccurate and misleading.

"For example, contrary to what has been alleged, we do currently pay above the National Living Wage for all employees and are committed to migrating towards the living wage foundation level over the next 18 months.

On the company's performance he said: "The strength of these results reflects our unwavering focus on delivering great customer experience, supported by rigorous execution of our investments."

A 31% fall in Asos' statutory pre-tax profit to £32.7m for the year to 31 August was partly explained by a £21m settlement in relation to a trademark infringement dispute with cycle wear manufacturer Assos of Switzerland.